Battery Vent Notch Geometry for Controlled Pressure Release
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Solution Overview
Problem
Secondary battery cells face the risk of thermal runaway due to uncontrolled pressure release, which can lead to a chain reaction of fires, necessitating improved vent structures to manage pressure safely.
Innovation Solution
A secondary battery cell with a vent structure featuring a base and a notch portion that satisfies specific relational expressions for thickness and width ratios, allowing controlled fracture at a predetermined pressure range of 0.7 to 0.9 MPa, ensuring safe gas release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vent structure is designed to release gas when internal pressure reaches a preset value, then safety against thermal runaway is improved, but control over the exact pressure release point becomes difficult
Solution Approach 1:
The patent applies parameter changes by precisely controlling the geometric dimensions of the notch portion (width b, thickness c) and base (thickness a) to determine the fracture pressure. By establishing specific mathematical relationships between these parameters (b/a and c/a ratios), the invention transforms the vent structure from a generic pressure relief device into a precisely controllable pressure release mechanism with predictable fracture points at desired pressure values.
Solution Approach 2:
The invention implements preliminary action by pre-designing the notch portion with specific dimensional relationships before the battery is put into service. The notch geometry is carefully calculated and manufactured in advance so that when internal pressure reaches the predetermined value, the vent structure fractures at the exact intended location, ensuring reliable and controlled pressure release without requiring real-time adjustment or complex control systems.
2Ease of manufacture
If the vent structure is made with a simple design, then manufacturing ease is improved, but the ability to control fracture pressure within a specific range (0.7-0.9 MPa) deteriorates
Solution Approach 1:
The patent resolves this contradiction by identifying the critical parameters that control fracture pressure (notch width b, notch thickness c, base thickness a) and establishing their optimal relationships. By focusing manufacturing precision on these specific dimensional parameters rather than the entire structure, the invention achieves precise fracture pressure control (0.7-0.9 MPa) while maintaining overall structural simplicity and ease of manufacture.
Solution Approach 2:
The invention applies local quality by concentrating the precision requirements on the notch portion geometry rather than the entire vent structure. The notch portion (with its specific width b and thickness c) is the only area requiring high manufacturing precision, while the rest of the vent structure can be manufactured with standard tolerances. This localized approach to quality control enables precise fracture pressure determination without significantly increasing overall manufacturing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The vent structure effectively fractures under desired pressure conditions, preventing thermal runaway and ensuring safety by controlled gas discharge.
Implementation Method 1
a vent portion that is opened when the inner space reaches a preset pressure range, and includes a base and a notch portion formed in the base
Data Source
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AI summary
A secondary battery cell according to an embodiment of the present disclosure may include: a case forming an inner space and including an opening on at least one side thereof; an electrode assembly arranged in the inner space and having a negative electrode and a positive electrode alternately stacked with a separator therebetween; a cap plate arranged to cover the opening; and a vent portion that is opened when the inner space reaches a preset pressure range, and includes a base and a notch portion formed in the base, wherein the notch portion satisfies relational expression 1 with the base. 1.2<100*b*c/a<2.9 (a: Thickness of base, b: Width of notch portion, and c: Thickness of notch portion)